Finned tube heat exchangers are widely used in a variety of applications in the fields of refrigeration, air conditioning and the like. Such heat exchangers consist generally of a plurality of spaced parallel tubes through which a heat transfer fluid such as water, oil, air or a refrigerant is forced to flow while a second heat transfer fluid such as air is directed across the tubes. To improve heat transfer a plurality of fins comprising thin sheet metal plates are placed on the tubes. Each fin plate has a plurality of apertures through which the tubes pass generally at right angles to the fin, and a large number of the fins are arranged in parallel, closely spaced relationship along the tubes to form multiple paths for the air or other heat exchange fluid to flow across the fins and around the tubes. The tubes and plates are provided with a suitable mechanical and thermal bond, for example by expansion of the tubes after assembly of the fin plates, to provide good thermal conduction. FIG. 1 of U.S. Pat. No. 4,365,667 illustrates an example of such heat exchangers, and is incorporated by reference.
A great number of different fin designs for heat exchangers have been proposed in the prior art in the continual search for efficiency, compactness and manufacturing and operating economy. Since the fins are so important in the overall heat transfer of the heat exchanger, even a small improvement in the fin can have an important beneficial effect on overall heat exchanger performance. Numerous fin designs have been proposed in the prior art.
Despite the progress which has been made in the field, there is still a need for a finned tube heat exchanger with excellent heat transfer efficiency and superior control of air pressure drop across the unit. At the same time stiffness in the heat exchanger fins is important to simplify and speed up assembly and manufacturing procedures.